nrf24l01+ crc problem

[LutzStiegler]

Hi,

I have been using nRF24 in many projects with Arduino. So far quite good experience.

Now I transfer to STM32 and have a strange problem, I cannot send with STM32 as MCU as soon as CRC is active (receive works fine). When I disable CRC (and of course Auto_ack off) everything works fine, stable and fast. As soon as I enable CRC only very view packages come through. I checked CRC length, payload length and all relevant registers on TX / RX device several times, have tried different modules from different sources, with power supply and tested different SPI configurations (although it looks fine, I can write and read registers reliably). Result always the same. I do not use any library on STM and the RF24  library by TMRh20 on Arduino. I have compared all possible register settings on both systems.

Currently I`m running on a STM32F407ZGT, use CubeMX (several versions tested) with HAL (several libraries tested).

I understand that the question for help is a bit abstract in that case, but what can go wrong when calculating CRC and how can I check / fix?

Thanks!

[Kenneth]

Have you tried sending payloads with the noack command? Make sure to add this feature on both PTX and PRX before you use it, this can be used to understand if it's actually the crc or/and other issue.

Best regards,
Kenneth

[LutzStiegler]

Hi Kenneth,

I have set REG_EN_AA to 0x00 on PTX and PRX side. But I have not send the payload with W_TX_PAYLOAD_NOACK method. 

Thanks for your help.

Lutz

[Kenneth]

Can you try the noack method? It would help understand if it's indeed crc or not.

Best regards,
Kenneth

[LutzStiegler]

OK, will test. What should be the status of REG_EN_AA and  EN_CRC for on PTX and PRX for that test?

[LutzStiegler]

OK - success.

It worked with noack method. Than I went step by step backwards until normal ESB with ack and now also that worked. I got curious what has actually changed and found the problem: When I clock in the payload at exactly the same size as  payload size in RX_PW_P0 it works. If the size doesnt match (actual payload to transmit smaller than value in RX_PW_P0) it doesnt work. That is a bit surprising as I havent interpreted the datasheet like this and it worked on Arduino - maybe something in the library that added the missing payload with zeros ... I will check. But now I know ...